A further cause, already hinted at above, for the arrest of intellectual progress is to be found in the growth of the nation in size during many centuries of isolation from the main stream of world-civilization, without that increase in heterogeneity which comes from the moulding by forces external to itself. “As iron sharpeneth iron, so a man sharpeneth the countenance of his friend.” Page 64Consequently we find China what is known to sociology as an ‘aggregate of the first order,’ which during its evolution has parted with its internal life-heat without absorbing enough from external sources to enable it to retain the plastic condition necessary to further, or at least rapid, development. It is in a state of rigidity, a state recognized and understood by the sociologist in his study of the evolution of nations.